1. Field of the Invention
This invention generally relates to integrated circuit (IC) fabrication and, more particularly, to a MOS transistor with a shallow metal oxide surface channel, and a method for fabricating the same.
2. Description of the Related Art
State-of-the-art CMOS transistors are often made using a gate material having a high work function, which corresponds to a high threshold voltage. For example, P+ polysilicon and N+ polysilicon (polySi) are used as the gate electrodes for nMOS and pMOS transistors, respectively. These poly gate transistors can be made using simple, lower cost fabrication processes, and the end product is reliable. High work function polySi gate electrodes are formed as a result of a high surface doping density. However, the high surface doping density reduces the electron and hole mobility, degrading transistor performance parameters such as switching time.
Gate electrodes can also be formed from metals, which have a relatively high work function as compared to polySi. However, metal gate transistors require the use of a different metal for nMOS transistors, than is used for pMOS transistors. This two-metal gate electrode approach adds to process complications and costs.
It would be advantageous if a high performance CMOS transistor could be fabricated, that also had a high work function.
It would be advantageous if the above-mentioned transistor could be fabricated without the use of highly doped polySi, or two-metal gate electrode materials.